In a large bowl, combine soy sauce, onions, rice wine vinegar, honey, cilantro, red pepper flakes, sesame seeds, ginger, garlic and sesame oil, and stir well to combine. Place the chicken in a large plastic bag or baking dish and cover with the marinade. Toss to combine and place in the refrigerator, turning frequently, to marinate at least 6 hours.

Preheat the grill to medium and the oven to 350 degrees F.

Remove the chicken from the marinade, reserving the marinade. Pat the chicken dry, and grill the chicken, skin-side up, until browned, about 10 minutes. Meanwhile, place the leftover marinade in a small saucepan and bring to a boil. Lower the heat to medium and simmer until slightly thick, about 10 minutes.

Turn the chicken, and grill until the skin is browned and crispy, about 5 minutes.

Baste the chicken with the marinade and continue cooking until done, another 5 - 10 minutes.

Arrange the chicken on a platter and put the leftover reduced marinade on a bowl on the side.